1. Field of the Invention
The present general inventive concept relates to an apparatus and a method to supply developer, and more particularly, to an apparatus and a method to evenly supply developer, which can control an operation speed or rotation speed of a conveying member that conveys the developer.
2. Description of the Related Art
A conventional electrophotographic developer process visualizes an electrostatic latent image and transfers the visualized image onto a printing medium. Such developer process generally uses a uni-component developer, which uses toner only, or bi-component developer, which uses carrier and toner in certain proportions.
It is important for a bi-component developer type of image forming apparatus to accurately control proportions of toner and carrier, that is, to control toner density at a stable proportion, in order to obtain a high-quality image. This can be done by setting a reference toner density that is based on the toner density detected by a sensing member from a predetermined area during a replacement of a developer.
However, toner density may vary because of surrounding conditions such as temperature or humidity, which can change toner fluidity. For example, toner flows relatively faster in low temperature, thus increasing flow rate of developer. Toner flows relatively slower in high temperature, thus decreasing a reference and flow rate. Even under the same temperature, the toner fluidity varies according to the degree of humidity. Therefore, toner fluidity is slower in high temperature and high humidity, than in high temperature and low humidity. Because a reference is decreased under high temperature and high humidity, image quality degrades. Because toner fluidity changes according to the surrounding factors such as temperature or humidity, toner density cannot be maintained as it is initially set, and this can decrease image quality.